Mussel-inspired polydopamine (PDA) particles with the size of ∼270 nm are used as a support of palladium (Pd) nanoparticles (NPs) for catalyst preparation. The surface morphology of the PDA particle has been modified via corrosion of CFCOOH. Surface chemistry of the obtained PDA particle has been engineered by the formation of a carboxylic acid-terminated alkanethiol monolayer. The obtained self-assembled monolayer-modified PDA (SAM-PDA) particles are used to load Pd NPs by simply adding HPdCl solution to a suspension of SAM-PDA particles at room temperature. Transmission electron microscopy, energy-dispersive X-ray mapping, dynamic light scattering, X-ray diffraction, X-ray photoelectron spectroscopy, UV-vis, and Fourier transform infrared are used to characterize the catalyst and to investigate the process. Uniform Pd NPs (2-3 nm) have been well-dispersed on the SAM-PDA particles via controllable surface engineering. Surface charges and interactions with a metal ion are regulated by the monolayer of carboxylic acids. The surface chemistry of PDA particles has been finely engineered for efficient loading of noble metal NPs. The obtained Pd/SAM-PDA catalyst has shown greatly increased activity and good reusability compared with Pd/PDA in the reduction of 4-nitrophenol (4-NP) by sodium borohydride or H. The kinetic data of 4-NP hydrogenation catalyzed by Pd/SAM-PDA are fitted to a Langmuir-Hinshelwood (L-H) model, and the calculated apparent activation energy of this process is 40.77 kJ mol.

Size control over metal−organic frameworks (MOFs) has been an important topic for this class of solid-state supramolecular materials. Herein, utilizing copper silicate as a solid metal source for the first time, we developed a novel environmentally friendly method to synthesize ultrasmall (5−9 nm) HKUST-1 nanoparticles supported on copper silicate nanotubes. Furthermore, by doping copper silicate nanotubes with other transition metal ions, many types of ultrasmall MOF nanoparticles (e.g., ZIF-8, ZIF-67, etc.) can be attained using the same approach. Compared with microsized MOFs synthesized through solution reaction from metal salts, these ultrasmall MOFs show extraordinary performance on organic dye adsorption. This research further sheds insight into the growth mechanism of MOF crystals using solid matters as metal sources, which allow us to employ ecofriendly feature from this general synthetic approach to construct intricate MOF nanocomposites.

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Solid acids as a substitution for hazardous liquid acids (e.g., HF and H 2 SO 4 ) can promote many important reactions in the industry, such as carbon cracking, to proceed in a more sustainable way. Starting from a zirconium-based metal-organic framework (UiO-66 nanocrystals), herein a transformative method is reported to prepare micro/mesoporous yttria-stabilized zirconia (YSZ) encapsulated inside a mesoporous silica shell. It is then further demonstrated that the resultant reactor-like catalysts can be used for a wide range of catalytic reactions. The acidity of the YSZ phase is found with rich accessible Lewis acid and Brønsted acid sites and they display superior performances for esterification (acetic acid and ethanol) and Friedel-Crafts alkylation (benzylation of toluene). After being loaded with different noble metals, furthermore, hydrogenation of CO 2 and a one-pot cascade reaction (nitrobenzene and benzaldehyde to N-benzylaniline) are used as model reactions to prove the versatility and stability of catalysts. Based on the findings of this work, it is believed that this class of reactor-like catalysts can meet future challenges in the development of new catalyst technology for greener heterogeneous catalysis. and thus their catalytic performances are determined to a great extent by their workable surface areas. Porous solid acids with high specific surface area can provide more accessible acid sites, which will significantly enhance catalyst efficiency. [2] Furthermore, compared with simply single pore size featured (e.g., micropore or mesopore) porous materials, hierarchical pore structures could endow them with better mass diffusion properties. [3] Meanwhile, functionalization of solid acids with active metal components has also been found to play a crucial role in many common reactions, such as the conversion of organic intermediates to synthetic drugs; [4] in those cases, engineering porosity for solid acid materials is also of vital importance because it endows them with a high loading capacity and uniform distribution of added components. Furthermore, topology of such supporting materials has been employed recently to resist sintering through size confinement, [5] which is one of the commonest impediments to nanoparticle catalysis. In this regard, ordered porous solid-acid catalysts could also play such a role to combat the sintering of their loaded metals. However, attention being devoted to this class of composite materials is found relatively lacking.On the other hand, in searching newer acid materials, it is recognized that metal-organic frameworks (MOFs) have drawn enormous attention in the last 20 years. Because of their high specific surface area, tunable porosity, and other functionalizable physicochemical properties, MOFs have been widely used in a variety of applications including molecular adsorptiondesorption, membrane separation, gas sensing, heterogeneous catalysis, encapsulation and controlled releases. [6] In particular, with coordinative unsaturation or open active metal sites on ...